This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Ongoing research in this project is aimed at characterizing the effects of normal aging on the memory processing functions of the hippocampus and related brain regions in rhesus monkeys. Subjects receive MRI scans and FDG PET imaging annually and the findings are evaluated in relation to signatures of age-related cognitive decline. Naturally occurring reproductive senescence is also tracked in order to test the influence of ovarian steroid decline on the neurocognitive outcome of aging.